Clutch piston and retraction spring subassembly and method of transmission assembly

ABSTRACT

This transmission has multiratio drive planetary gearing and a plurality of fluid actuators for selectively engaging a plurality of friction devices to engage the ratio drives. A central web splined to the transmission housing has oppositely facing fluid actuators each having an annular piston in a cylinder. Each piston has an inner annular engagement seat and an outer interrupted annular engagement seat for engaging the brake plates with retraction springs and fastener posts located between the seats. A retainer plate has an annular portion between the seats engaging the springs, an aperture for receiving the fastener posts and ear portions extending into engagement with the web. Snap rings hold the retainer plates and web against axial movement. A fastener on each fastener post holds the retainer plate, piston and springs in assembled position for assembly into the cylinder of the transmission.

United States Patent [72] Inventor ErkkiA.Koivunen Livonia, Mich.

[21] App]. No. 832,168

[22] Filed June 11, 1969 [45] Patented Aug. 3, 1971 [73] AssigneeGeneral Motors Corporation Detroit, Mich.

[54] CLUTCH PISTON AND RETRACTHON SPRING SUBASSEMBLY AND METHOD OFPrimary Examiner-Arthur T. McKeon Attorneys-E. W. Christen and A. M.Heiter ABSTRACT: This transmission has multiratio drive planetarygearing and a plurality of fluid actuators for selectively engaging aplurality of friction devices to engage the ratio drives. A central websplined to the transmission housing has oppositely facing fluidactuators each having an annular piston in a cylinder. Each piston hasan inner annular engagement seat and an outer interrupted annularengagement seat for engaging the brake plates with retraction springsand fastener posts located between the seats. A retainer plate has anannular portion between the seats engaging the springs, an aperture forreceiving the fastener posts and ear portions extending into engagementwith the web. Snap rings hold the retainer plates and web against axialmovement. A fastener on each fastener post holds the retainer plate,piston and springs in assembled position for assembly into the cylinderof the transmission.

ClLiUT Clh'l PTSTUN AND lltlETTtflrC'llllUhi SiPlitihlGSUllitASdhli/llhli! AND MlE'llll-TUD @ll TTTANSMIISSTUN ASSlEMihLT Thisinvention relates to transmissions and particularly to an improved fluidactuated ratio establishing friction device and bearing supportstructure for gearing providing simplified assembly and an improvedmethod of assembly.

Transmission constructions which require assembly of many complex partson different splines, the use of many snap rings and the compression ofthe retraction springs for the pistons of the fluid actuators duringassembly of the transmission parts in the housing present a difficultand expensive assembly operation.

Transmissions, in addition to meeting the drive requirements of thevehicle in which they are used, should have a simple structural supportarrangement which can be easily assembled to insure uniform assembly forreliability and reduction of initial and repair costs. in accordancewith this invention the number and complexity of the parts is reduced,particularly the number of snap rings and the fluid actuator devices andtheir retraction springs are preassembled with the springs compressed tofacilitate transmission assembly.

The object of the invention is to provide an improved transmission tofacilitate and simplify assembly.

Another object of this invention is to provide a fluid actuatorpreassembly having a movable actuator member with a retainer membersecured to said movable actuator member only to prevent separatingmovement to hold the retraction springs between these members and permitapply movement in the final assembly.

Another object of the invention is to provide an improved fluid actuatorin which the piston is located in the cylinder and retraction springsare precompressed between the piston and the retraction plate which issecured to the piston by a fastener to hold the retraction springscompressed but which permits apply movement during fluid operation ofthe fluid actuator.

Another object of the invention is to provide an improved method ofassembling a transmission in which the retraction springs are placed onthe movable actuator member and a retainer plate is attached to themovable actuator member to prevent only separating movement to hold thesprings in position to provide a preassembly for positioning a finedactuator member.

Another object of this invention is to provide improved fluid actuatorand friction device components of a transmission to facilitate assemblyinto a transmission housing.

These and other objects and advantages will be apparent to those skilledin the art from the following description and drawings.

FIG. 1 shows a partial cross section of the transmission gearing andfluid actuated friction devices.

FIG. 2 is a section on line 2-2 of HG. ll showing details of the fluidactuator.

HO. 3 is an exploded view of the fluid actuator.

DESClUPTlON OF THE DRAWTNGS Referring to FlG. ii, there is atransmission having a housing it] which enclosed a torque converter, ahydraulic pump not shown but fully described in application Ser. No.805,190 Power Transmission, filed Mar. 7, 1969 by John J. ()Malley andshowing three planetary gear sets lib, ill and 20.

A torque converter of conventional construction transmits power from theengine to the transmission gearing through input shaft 3 6 splined to aclutch housing 3%. The clutch housing 3% is drivingly connected to twoinput clutches All] and 42.

The input clutch dill includes a plurality of alternately spaced platesMl and as which are splined to the clutch housing 38 and a hub dbrespectively. A piston fill is slidably mounted in a fluid chamber 52 inthe clutch housing 38. The fluid pressure in chamber 52 urges the piston54) to engage the clutch plates 4M! and do to the clutch ill). Thereturn spring 54 is held in compression between the piston 50 and aspring retainer 56 which is mounted on the housing 3%. The return spring5d moves the piston 50 out of engagement with the clutch plate when thechamber 52 is not pressurized. A passage 5b in the housing Eltll isadapted to supply fluid to the chamber 52.

The clutch 32i includes a plurality of alternately spaced plates tiltand as which are splined to the clutch housing 38 and to a drum lidrespectively. A position rib is slidably mounted in chamber oil in drumM. The chamber is pressurized to engage the clutch M. A passage 70 indrum M conveys fluid pressure to chamber till. A return spring '72 iscompressed between the piston titi and a spring retainer 74 mounted ondrum tin and functions to move the piston out of engagement when thechamber ss is not pressurized. A brake "/"d is also operativelyconnected with the drum M and includes alternately spaced plates 7bsplined to the drum M and plates hill having four or more sets of spacedpairs of teeth tit) extending from the outer perimeter which fit in fouror more spaced pairs of spline recesses 90. The splines W are axiallyshort and only extend from W to 9b", the length of the clutch platesTb-ht), snap ring fi l, backing plate 75 and snap ring 7'7, so the casemay be cast with a one piece core and axially drawn. The draft in theseshort splines does not provide excessive clearance at the thin or frontends. The web M is rotatably fixed by fittings, such as fitting 94! forline 94 and axially located between snap rings 91 and 93 in grooves inthe transmission housing 110. The fitting W is shown at the top of thehousing for convenience but is usually at the bottom adjacent the valvebody not shown. A piston or movable actuator member b2 is slidablymounted in the annular chamber or cylinder b6 having annular sidewallsand a transverse wall formed in the central web lid. When chamber 86 inthe fixed actuator or web is filled with pressure fluid piston 82 movesto engage the brake '76.

The plates of brake 76 are located between the fixed baclting orabutment plate 75 located by snap ring 77 in a groove in splines ill)and housing l0 and the annular actuator apply face on inner actuatorannulus 79 and the interrupted annular face or outer actuator annulus b1both on piston 82. The outer actuator annulus bl has gaps therein forcars 87 of retainer plate b7. Fastener posts b3 are fixed or integralwith the transverse wall of the piston or movable actuator between theannuluses providing the apply faces. The transverse wall has a fluidconfining face facing in the direction into the cylinder.

A plurality of coil return springs 8b seated in round pockets betweenannuluses 79 and 811 engage the annular spring retainer plate d7 whichis fixed in a groove 84 in the fixed actuator or central web M andretained therein by wedge snap ring ill to bias the piston out ofengagement with the plates 7% and bi) when the brake is disengaged. Notethat retainer plate 87 has an annular portion 87 between the inner andouter actuator annuluses 79 and 811 engaged by the springs b8 andanchoring ear portions 87" extending; through the interruptions or gapsbetween the parts of the interrupted annular outer actuator portion toseat in the groove 84' in web 84. Openings or holes h7a in the retainerplate 87 fit over posts 83 to guide and locate the retainer plate withrespect to the piston 82.

The friction fastener 89 slips on the post 83 and holds the piston b2and retainer plate 87 at a fixed maximum distance apart with theretraction springs b8 preferably partially compressed and almost in thefully retracted position. This subassembly remains as assembled duringtransmission assembly and disassembly. When the transmission isassembled as pointed out below the wedge snap ring 91 moves the retainerplate b7 sufficiently to relieve the spring load on fastener 89. Thesprings and posts are symmetrically distributed about the annulus toprovide a balanced retraction force and load on the attachable fastenermeans, post b3 and fastener 39.

The central web as is rotatably secured to the transmission housing byfittings, i.e. fitting 9d and has a plurality of fluid passages 92;, 9dand 96 which are adaptive to supply pressure to the clutch 42, the brake76 and brake 98 respectively as shown in detail in the above Ser. No.805,190.

Brake 98 has plates 122-124 abutting the fixed abutment plate 125 whichis axially positioned by the step 1238 in spline recess 123. The plates124 have a plurality of pairs of ears 124' and the abutment plate 125has similar ears 125' which fit in the spline recesses 123 arranged in aplurality of pairs about the perimeter. The short spline 123 from end123 to end 123" has minimum draft to avoid excessive clearance in theforward splines. As shown in FIG. 2 a clearance recess 223 extendsforwardly in the housing between spline recesses 90 so the rear platescan be assembled from the open front of the transmission housing and sothis long recess can have maximum draft. This access recess is generallywider than both spline recesses. Thus web 84 is piloted by thecylindrical internal diameter of the housing which is only interruptedby recesses 223.

Piston 126 is like piston 82 with springs 130 seated in round holes orseating pockets 127 between the inner engagement seat 129 and the outerinterrupted annular engagement seat 131. The annular retainer 133 has anannular portion 135 engaging springs 130 and ears 137 extending betweenthe portions of the interrupted engagement seat 131 into a groove in web84 and retained therein by snap ring 93. As in piston 82, piston 126 hasa fastener post between each group of retainer springs extending throughan opening in the annular portion of the retainer ring and a fastener tohold the retainer plate and springs in assembled position. The web 84also provides rotational support for an intermediate sleeve shaft 104which is splined to the drum 64 and for an intermediate shaft 106 whichis splined to the hub 48 and rotatably journaled in the sleeve shaft104.

The sleeve shaft 104 is splined to a pair of sun gears 108 and 110 whichare components of the planetary gear sets 16 and 18 respectively. Theplanetary gear set 16 also includes a plurality of planet pinions 112which are rotatably mounted in a carrier 114 and mesh with the sun gear108 and a ring gear 1 16 which is drivingly connected to a carrier 118of the planetary gear set 18 and a carrier 129 which is a member of theplanetary gear set 20. The carrier 114 is operatively connected to thebrake 98 which includes the plurality of alternately spaced plates 122and 124 which are splined to the carrier 114 and'the housingrespectively. The piston 126 is slidably mounted in annular cylinder orchamber 128 in the central web 84. The chamber 128 is filled withpressure fluid via passage 96 to engage the brake 98. A plurality ofreturn springs 130 are provided to move the piston 126 out of engagementwith the brake plates 122-124 to disengage the brake 98 when the chamber128 is not pressurized.

The planetary set 18 includes a plurality of pinion gears 132 which arerotatably mounted on the carrier 118 and mesh with the sun gear 110 anda ring gear 134 which is drivingly connected through a hub 136 with asun gear 138 of the planetary set 20. The ring gear 134 and the sun gear138 are splined to the intermediate shaft 106 which is connected to theinput clutch 40.

The planetary set also includes a plurality of pinion gears 140 whichare rotatably mounted on the carrier 120 and mesh with the sun gear 138and a ring gear 142. The carrier 120, the carrier 118 and the ring gear116 are drivingly connected to the transmission output shaft 144. Thering gear 142 is operatively connected to a brake 146 which includes aplurality of alternately spaced plates 148 and 150 which are splined tothe splines 151 in the transmission housing 10 and the ring gear 142respectively. The splines 151 are cast axially draftable splines at asmaller diameter than splines 90 and so the housing is an axiallydraftable casting. A piston 152 is slidably disposed in chamber 154 inthe transmission housing 10. When apply chamber 154 is filled withpressure fluid, the piston 152 engages the plates 148-150 therebyapplying the brake 146. A plurality of return springs (not shown) areprovided to move the piston 152 out of engagement with the brake plateswhen the chamber 154 is not pressurized.

Rotation of pistons 84 and 126 may be prevented by pins 161 set in boresin web 84 and fitting recesses 162 in ears B7" of spring retainer 87which engages the piston 82 at the edge of ears 87" fitting in the gapsbetween the portions of interrupted actuator annulus 81 or at theaperture 87a for post 83. Also half circular abutments 163 and 164 or anabutment and fitting recess on the web 84 and piston 82 may preventrotation of the piston.

The clutches and brakes described above are actuated by fluid pressurein the manner described in the above Ser. No. 805,190.

The clutch 40, when engaged, provides a drive connection from the torqueconverter or input to the sun gear 138 and ring gear 134. The clutch 42,when engaged, provides a drive connection from the torque converter orinput to the sun gears 108 and 110. The brake 76, when engaged,restrains the sun gears 108 and from rotation to thereby establish sungear 110 as a reaction member. Brake 98 restrains carrier 114 fromrotation and thereby establishes the carrier as a reaction member. Thebrake 146 restrains the ring gear 142 from rotation and therebyestablishes the ring gear as a reaction member. To provide first geardrive forward, the clutch 40 and the brake 146 are engaged thusproviding a simple planetary reduction in the planetary gear set 20.

To establish second gear forward, the brake 146 is disengaged while thebrake 98 is engaged and the clutch 40 remains engaged to provide acompound reduction drive in planetary gear sets 18 and 16 between theinput shaft 34 and the output shaft 144. in second gear forward, thering gear 134 is the input member for the planetary gearing and ringgear 116 and carrier 118 are output members. The planetary set 20 merelyidles and carries no load.

To establish third gear forward, the brake 98 is disengaged while thebrake 76 is engaged and the clutch 40 remains engaged thus providing asimple planetary reduction in planetary gear set 18 between the inputshaft 34 and the output shaft 144. The ring gear 134 is also the inputmember in third gear forward and the carrier 118 is the output member.

To establish fourth gear forward, the brake 76 is disengaged while theclutch 42 is engaged and the clutch 40 remains engaged. With bothclutches 40 and 42 engaged, the planetary sets 16, 18 and 20 are in alockup or one-to-one condition thus providing a direct drive from theinput shaft 34 to the output shaft 144.

To establish one reverse ratio, the clutch 42 is engaged and the brake146 is engaged. This provides a compound reverse reduction ratio inplanetary gear sets 18 and 20 between the input shaft 34 and the outputshaft 144. In this reverse drive, the sun gear 1 10 is the input memberand the carrier is the output member for the planetary gear sets.

To establish another reverse ratio, the brake 146 is disengaged whilethe brake 98 is engaged and the clutch 42 remains engaged. Thisestablishes a simple planetary reverse reduction drive in planetary gearset 16 between the input shaft 34 and the output shaft 144. In thisdrive, the sun gear 108 is the input member and the ring gear 116 is theoutput member of the planetary gear set.

This transmission structure facilitates manual or automatic assembly ofthe transmission. The piston or movable actuator member 82 ispreassembled with the springs 88 and retainer plate 87 and secured byfastener 89. This preassembly is made by inserting springs 88 in thespring pockets 85 which hold the springs in place. Then the retainerplate is placed in position to be moved between the annuluses 79 and 81with the ears 87 in the gaps in outer annulus 81 by aligning holes 87awith posts 83 and moving the retainer plate toward the piston andcompressing the springs until the retainer plate is below the actuatorfaces. Then the fastener is placed on the post to hold the preassemblytogether with the springs having the desired degree of precompressionand ready to move or be further compressed in the actuating stroke whenassembled with the cylinder or fixed actuating member. Then this pistonpreassembly is placed in the cylinder until the piston bottoms on thecylinder at stop portions M on the piston and cylinder and the ears W"on the retainer plate partially enter the groove M at the free end ofthe annular wall of cylinder as to hold the piston in the fullyretracted position of its operating stroke. Then piston lilo, springs1139 and retainer plate I133 are similarly assembled and inserted incylinder 12%.

Then the transmission parts are assembled through the front open end ofhousing 10. The piston R52, which may be an assembly like piston 82 isinserted in chamber TM and the plates Manse and backing member areplaced in the rear splines and secured by a snap ring. Then the gearunit is assembled in position. Then the backing plate T25 is placed onsplines 123 against stop shoulder 112358 and plates TEE-112 iare placedon these splines against the backing plate. The snap ring 93 is theninserted. The preassembled web Ml and pistons 82 and 1126 are theninserted with the ears of retainer plate 1133 en gaging ring 393. Thewedge snap ring M is inserted and engages the web and retains the earsof retainer plate @7 so both retainer plates are retained with a smallclearance in the grooves in the web. This movement of the retainerplates toward each other by the wedge snap ring compresses theretraction springs a small additional amount to provide a smallclearance between the fasteners and the retainer rings to relieve theload on the fasteners $9 when they are thus assembled in the housing.Note that the wedge snap ring 91 has a bottom clearance so regardless oftolerance variations, it seats on and holds the web against ring 93. Theweb seats in a pilot bore through which the recesses 223 extend and issecured against rotation by fittings M. The friction plates 73, 80 andbacking plate '75 are then assembled in the splines and located by snapring '77. Then the clutch assemblies 42 and 38 are inserted in thehousing.

Each of spline recesses $96 1123 and llll are short axially draftablesplines which have a small minimum draft. The long draft of accessrecess 223 for the rear spline is merely an access recess and has aslarge a draft as desired. The rear splines are short and at a smallerdiameter. Thus rear splines, central splines and front splines with apilot diameter between the central and front splines may be cast with anaxially draftable core.

It should be understood that the above description is of an exemplaryembodiment and that obvious modifications will occur to those skilled inthe art.

What is claimed is:

1. In a fluid actuator device; movable actuator means having wall meanshaving a fluid confining face facing in one axial direction, a springseat facing in the opposite direction and a partial actuator portionextending from said wall means in said opposite direction and having anactuator face for applying a force in said opposite direction spaced asubstantial axial distance from said spring seat; retainer meanslaterally spaced from said partial actuator portion, axially locatedbetween said actuator face and said spring seat for permitting relativemovement through a distance and having a spring abutment portion facingsaid spring seat; a spring positioned between said spring seat and saidspring abutment portion and attachable fastening means on said actuatormeans and retainer means to limit separating movement of said retainermeans from said movable actuator means to hold said spring in saidposition between said actuator face and spring seat and permittingrelative movement of said retainer means and movable actuator meanstoward each other during compression of said spring.

2. The invention defined in claim 1 and fixed actuator means cooperatingwith said wall means of said movable actuator means for forming anexpansible chamber therebetween contracting on movement of said movableactuator means in said one direction and expanding on movement of saidmovable actuator means in said opposite direction; securing positioningmeans on said fixed actuator means for engaging said retainer means;stop means on said fixed actuator means and movable actuator means tostop said contracting movement at the fully contracted position withsaid fastening means limiting separating movement of said movableactuator means and said retainer means spaced a small distance from saidsecuring positioning means.

3. The invention defined in claim 2 and detachable fastening meansoperably connected between said fixed actuator means and said retainermeans for securing said retainer means against said securing positioningmeans to position said retainer means for a slight further compressionof said spring relieving the load on said attachable fastening means andproviding for further compression of said spring during said expandingmovement on the application of said movable actuator.

d. The invention defined in claim 3 and a transmission housing having anaxial abutment; said fixed actuator means being rotatably fixed to saidhousing and engaging said axial abutment to limit movement in said onedirection; said detachable fastening means being fixed to said housingto hold said retainer means against said fixed actuator means and saidfixed actuator means against said axial abutment; drive means includinga friction device for providing a reaction for establishing a drive; andmeans operably connecting said friction device to said housing andlimiting axial movement in said opposite direction.

5. ma fluid actuator device; movable annular actuator means havingannular wall means having an annular fluid confining face facing in oneaxial direction, a plurality of spring seats facing in the oppositedirection annularly distributed for balanced force application and aninner and outer actuator annulus with one actuator annulus having gapstherein extending axially from said wall means in the opposite directionand each having an annular actuator face for applying a force in saidopposite direction spaced a substantial axial distance from said springseats; retainer means having an annular spring abutment portion locatedlaterally between said actuator annuluses and axially between saidspring seats and said annular actuator face for relative movement; aplurality of springs trapped between said spring seats and said annularspring abutment portion and attachable fastening means to limitseparating movement of said retainer means from said movable actuatormeans to hold said springs in place and permitting relative movement ofsaid retainer means and movable actuator means toward each other duringcompression of said springs.

6. The invention defined in claim 5 and said attachable fastener meansconsisting of an opening in said retainer means; a post fixed to saidmovable actuator means extending through said opening and a fastenersecured to said post and engaging said retainer means on the sideopposite said springs.

7. The invention defined in claim 6 and said retainer means havinganchoring ears extending through the gaps in said one actuator annulus.

it. The invention defined in claim '7 and fixed actuator meanscooperating with said wall means of said movable actuator means formingan expansible chamber therebetween which contracts on movement of saidmovable actuator means in said one direction and expands on movement insaid opposite direction and having stop means engaging said movableactuator means to stop said contracting movement of said movableactuator means at the fully contracted position and securing positioningmeans on said :fixed actuator means slightly spaced from said ears atsaid fully contracted position.

9. The invention defined in claim 8 and detachable fastening meansoperably connected between said fixed actuator means and said retainermeans ears for holding said retainer means against said securingpositioning means slightly compressing said springs and removing theload on said attachable fastening means and assuming the spring load inthe fully contracted position and during said expanding movement of saidmovable actuator further compressing said springs.

110. The invention defined in claim 9 and a transmission having ahousing with an internal bore having splines with an open end and anaxial abutment at the other end; drive means rotatably mounted in saidhousing having a reaction element having friction plates rotatable withthe reaction element and fixed plates splined to said splines; saidfixed actuator being located in said bore, held against rotation andengaging said axial abutment to limit movement in said one direction; asingle detachable wedge locating ring compressing said springs torelieve the load on said fastening means and holding both said fixedactuator means against said axial abutment and holding said retainermeans fixed with respect to said housing; said plates being positionedfor engagement on one side by said actuator face for applying saidfriction device; a backing plate engaging said plates on the other sideand securing means securing said backing plate to said housing.

11. The invention defined in claim 9 and said fixed actuator means beingan annular cylinder having wall means including a transverse wall andannular sidewalls: said movable actuator means having said annular wallmeans and said annuluses between said annular sidewalls and saidannuluses extending beyond the free ends of said annular sidewalls.

12. In a transmission a cast housing having an open end; planetary gearmeans rotatably mounted in said housing having a first and a secondbrake each operative to brake an element to establish ratio drives; eachbrake having a backing plate and a set of alternate friction plateshaving a plurality of circumferentially spaced sets of external teethand intermediate friction plates connected to an element; said housinghaving a first group of sets of spline recesses spaced circumferentiallya greater distance than the circumferential length of each set of splinerecesses, extending axially a short distance and having minimum axialdraft to substantially fit said external teeth and a second group ofsets of spline recesses spaced circumferentially a greater distance thanthe circumferential length of each set of spline recesses, extendingaxially a short distance and having minimum axial draft to substantiallyfit said external teeth located axially further from the open end ofsaid housing and located circumferentially between the spaced sets ofsaid first group of spline recesses access recesses having at least aslarge a circumferential width as said sets of spline recesses extendingaxially and located between said sets of spline recesses of said firstgroup and aligned with said sets of spline recesses of said secondgroup; said second set of alternate friction plates being movablethrough said access recesses and positioned with said external teeth insaid second group of spline recesses; said first set of alternatefriction plates being positioned with said external teeth in said firstgroup of spline recesses; means to limit axial movement of said backingplates and means to provide an apply force acting on said frictionplates to engage said brakes.

13. The invention defined in claim 12 and said backing plates andalternate friction plates having identical sets of external teeth.

14. The invention defined in claim 13 and said first and second groupsof spline recesses being spaced apart to provide a pilot bore traversedby said access recesses and said means to provide an apply force being amember piloted in said pilot bore, secured against movement and havingopposed cylinders with a piston in each of said cylinders and eachpiston having an apply portion for engaging the adjacent friction plate.

15. The invention defined in claim 14 and said access recess having alarge draft.

16. The invention defined in claim 14 and a retainer ring extendingbetween each of said pistons and the adjacent friction plate andengaging an adjacent portion of said member; spring means between eachretainer ring and the adjacent piston; retainer means to axiallyposition said member and said retainer rings with said springs meanscompressed and biasing said pistons to the retracted position and oneway limit fastener means on each piston engaging the adjacent retainerring permitting free apply movement of said piston relative to saidadjacent retainer ring and preventing movement of said retainer ringaway from said piston on release of said retainer means to hold saidspring means partially compressed.

1. In a fluid actuator device; movable actuator means having wall meanshaving a fluid confining face facing in one axial direction, a springseat facing in the opposite direction and a partial actuator portionextending from said wall means in said opposite direction and having anactuator face for applying a force in said opposite direction spaced asubstantial axial distance from said spring seat; retainer meanslaterally spaced from said partial actuator portion, axially locatedbetween said actuator face and said spring seat for permitting relativemovement through a distance and having a spring abutment portion facingsaid spring seat; a spring positioned between said spring seat and saidspring abutment portion and attachable fastening means on said actuatormeans and retainer means to limit separating movement of said retainermeans from said movable actuator means to hold said spring in saidposition between said actuator face and spring seat and permittingrelative movement of said retainer means and movable actuator meanstoward each other during compression of said spring.
 2. The inventiondefined in claim 1 and fixed actuator means cooperating with said wallmeans of said movable actuator means for forming an expansible chambertherebetween contracting on movement of said movable actuator means insaid one direction and expanding on movement of said movable actuatormeans in said opposite direction; securing positioning means on saidfixed actuator means for engaging said retainer means; stop means onsaid fixed actuator means and movable actuator means to stop saidcontracting movement at the fully contracted position with saidfastening means limiting separating movement of said movable actuatormeans and said retainer means spaced a small distance from said securingpositioning means.
 3. The invention defined in claim 2 and detachablefastening means operably connected between said fixed actuator means andsaid retainer means for securing said retainer means against saidsecuring positioning means to position said retainer means for a slightfurther compression of said spring relieving the load on said attachablefastening means and providing for further compression of said springduring said expanding movement on the application of said movableactuator.
 4. The invention defined in claim 3 and a transmission housinghaving an axial abutment; said fixed actuator means being rotatablyfixed to said housing and engaging said axial abutment to limit movementin said one direction; said detachable fastening means being fixed tosaid housing to hold said retainer means against said fixed actuatormeans and said fixed actuator means against said axial abutment; drivemeans including a friction device for providing a reaction forestablishing a drive; and means operably connecting said friction deviceto said housing and limiting axial movement in said opposite direction.5. In a fluid actuator device; movable annular actuator means havingannular wall means having an annular fluid confining face facing in oneaxIal direction, a plurality of spring seats facing in the oppositedirection annularly distributed for balanced force application and aninner and outer actuator annulus with one actuator annulus having gapstherein extending axially from said wall means in the opposite directionand each having an annular actuator face for applying a force in saidopposite direction spaced a substantial axial distance from said springseats; retainer means having an annular spring abutment portion locatedlaterally between said actuator annuluses and axially between saidspring seats and said annular actuator face for relative movement; aplurality of springs trapped between said spring seats and said annularspring abutment portion and attachable fastening means to limitseparating movement of said retainer means from said movable actuatormeans to hold said springs in place and permitting relative movement ofsaid retainer means and movable actuator means toward each other duringcompression of said springs.
 6. The invention defined in claim 5 andsaid attachable fastener means consisting of an opening in said retainermeans; a post fixed to said movable actuator means extending throughsaid opening and a fastener secured to said post and engaging saidretainer means on the side opposite said springs.
 7. The inventiondefined in claim 6 and said retainer means having anchoring earsextending through the gaps in said one actuator annulus.
 8. Theinvention defined in claim 7 and fixed actuator means cooperating withsaid wall means of said movable actuator means forming an expansiblechamber therebetween which contracts on movement of said movableactuator means in said one direction and expands on movement in saidopposite direction and having stop means engaging said movable actuatormeans to stop said contracting movement of said movable actuator meansat the fully contracted position and securing positioning means on saidfixed actuator means slightly spaced from said ears at said fullycontracted position.
 9. The invention defined in claim 8 and detachablefastening means operably connected between said fixed actuator means andsaid retainer means ears for holding said retainer means against saidsecuring positioning means slightly compressing said springs andremoving the load on said attachable fastening means and assuming thespring load in the fully contracted position and during said expandingmovement of said movable actuator further compressing said springs. 10.The invention defined in claim 9 and a transmission having a housingwith an internal bore having splines with an open end and an axialabutment at the other end; drive means rotatably mounted in said housinghaving a reaction element having friction plates rotatable with thereaction element and fixed plates splined to said splines; said fixedactuator being located in said bore, held against rotation and engagingsaid axial abutment to limit movement in said one direction; a singledetachable wedge locating ring compressing said springs to relieve theload on said fastening means and holding both said fixed actuator meansagainst said axial abutment and holding said retainer means fixed withrespect to said housing; said plates being positioned for engagement onone side by said actuator face for applying said friction device; abacking plate engaging said plates on the other side and securing meanssecuring said backing plate to said housing.
 11. The invention definedin claim 9 and said fixed actuator means being an annular cylinderhaving wall means including a transverse wall and annular sidewalls:said movable actuator means having said annular wall means and saidannuluses between said annular sidewalls and said annuluses extendingbeyond the free ends of said annular sidewalls.
 12. In a transmission acast housing having an open end; planetary gear means rotatably mountedin said housing having a first and a second brake each operative tobrake an element to establish ratio drives; eacH brake having a backingplate and a set of alternate friction plates having a plurality ofcircumferentially spaced sets of external teeth and intermediatefriction plates connected to an element; said housing having a firstgroup of sets of spline recesses spaced circumferentially a greaterdistance than the circumferential length of each set of spline recesses,extending axially a short distance and having minimum axial draft tosubstantially fit said external teeth and a second group of sets ofspline recesses spaced circumferentially a greater distance than thecircumferential length of each set of spline recesses, extending axiallya short distance and having minimum axial draft to substantially fitsaid external teeth located axially further from the open end of saidhousing and located circumferentially between the spaced sets of saidfirst group of spline recesses access recesses having at least as largea circumferential width as said sets of spline recesses extendingaxially and located between said sets of spline recesses of said firstgroup and aligned with said sets of spline recesses of said secondgroup; said second set of alternate friction plates being movablethrough said access recesses and positioned with said external teeth insaid second group of spline recesses; said first set of alternatefriction plates being positioned with said external teeth in said firstgroup of spline recesses; means to limit axial movement of said backingplates and means to provide an apply force acting on said frictionplates to engage said brakes.
 13. The invention defined in claim 12 andsaid backing plates and alternate friction plates having identical setsof external teeth.
 14. The invention defined in claim 13 and said firstand second groups of spline recesses being spaced apart to provide apilot bore traversed by said access recesses and said means to providean apply force being a member piloted in said pilot bore, securedagainst movement and having opposed cylinders with a piston in each ofsaid cylinders and each piston having an apply portion for engaging theadjacent friction plate.
 15. The invention defined in claim 14 and saidaccess recess having a large draft.
 16. The invention defined in claim14 and a retainer ring extending between each of said pistons and theadjacent friction plate and engaging an adjacent portion of said member;spring means between each retainer ring and the adjacent piston;retainer means to axially position said member and said retainer ringswith said springs means compressed and biasing said pistons to theretracted position and one way limit fastener means on each pistonengaging the adjacent retainer ring permitting free apply movement ofsaid piston relative to said adjacent retainer ring and preventingmovement of said retainer ring away from said piston on release of saidretainer means to hold said spring means partially compressed.